1. Field
A liquid crystal panel that can control a viewing angle of an image and a liquid crystal display device (LCD) with the liquid crystal panel is provided.
2. Related Art
A liquid crystal display device (LCD) displays an image by controlling the strength of an electric field applied to a liquid crystal panel such that the quantity of light penetrating the liquid crystal panel is adjusted. The liquid crystal panel is the main component of the LCD. The liquid crystal panel uses external light to display an image, and thus has a limited viewing angle. An in-plane switching (IPS) mode that uses an horizontal electric field, a mode that uses a compensation film, and a multi-domain mode that uses a protrusion or an opening pattern on a transparent electrode are introduced to enhance the limited viewing angle of the liquid crystal panel.
Users of data terminals, for example, portable phones, personal digital assistants (PDAs) and computers desire that the displayed data is prevented from being viewed by others. To meet such a demand, an LCD used as a display device of the data terminals needs to provide a narrow viewing angle mode as well as a wide viewing angle mode.
A dual-structure liquid crystal panel has been proposed to meet the need for the multiple viewing angle mode.
FIG. 1 is a sectional view of a related art dual-structure liquid crystal panel capable of controlling a viewing angle. Referring to FIG. 1, the related art dual-structure liquid crystal panel includes a normal panel 10 and an interference panel 12 disposed on the normal panel 10. The normal panel 10 displays an image, while the interference panel 20 causes light traveling in the side directions to be interfered with. This dual-structure liquid crystal panel can change a viewing angle mode using the light interference operation of the interference panel 12.
An LCD including the dual-structure liquid crystal panel selectively drives the interference panel 12 to provide both a wide viewing angle mode and a narrow viewing angle mode. That is, the interference panel 12 is turned on or off to provide the narrow viewing angle mode or the wide viewing angle mode.
In the dual-structure liquid crystal panel, an external light must penetrate two liquid crystal layers and thus the brightness of an image is greatly reduced. Also, the dual-structure liquid crystal panel is thicker and heavier than a single-structure liquid crystal panel. Moreover, even in the narrow viewing angle mode, an image viewed from the front side, as illustrated in FIG. 2A, is also viewed dimly at the left and right sides, as illustrated in FIGS. 2B and 2C. This makes it difficult to ensure the secrecy of a user.